Air-assisted fuel injection system

ABSTRACT

A number of embodiments of induction systems for internal combustion engines having fuel injector which spray fuel into the intake passages serving the individual combustion chambers. An arrangement is provided for injecting auxiliary air into the intake passages at atmospheric pressure. The timing and duration of air injection is varied so as to reduce pumping losses, control internal EGR, induce turbulence in the combustion chamber, control idle speed and to atomize the fuel injected by the fuel injectors, and, if desired, redirect it. Various valving and timing arrangements are disclosed whereby the duration and timing of the air injection can be controlled. In addition, embodiments are disclosed having insert pieces through which the fuel is injected and redirected by the air injected.

This application is a divisional of U.S. patent application No.08/442,196, filed May 16, 1995; now U.S. Pat. No. 5,623,904.

BACKGROUND OF THE INVENTION

This invention relates to an induction system for an engine and moreparticularly to an air assisted fuel injection system for engines.

The use of fuel injection systems is becoming relatively commonplace,particularly in automotive applications. Fuel injection offers greatercontrol of the fuel-air mixture than carburetors and thus offersimprovements in both fuel economy and exhaust emission control. The fuelinjector may inject fuel either directly into the combustion chamber orinto the induction passage for induction along with the intake air intothe combustion chamber. Regardless of which system is employed, it isdesirable that the fuel delivered by the fuel injector is well atomizedand mixed with the air.

Systems have been proposed wherein air under high pressure is injectedalong with the fuel. These systems are thought to improve fueldispersion and atomization. However, the systems proposed for thispurpose require relatively high air pressures and hence the engine mustbe provided with an air compressor, a drive for the air compressor andin many instances, regulation units for regulating the air pressure. Thecomplexity of these systems at many times offsets their advantages.

Another type of system has been proposed, particularly for inductionsystem injection, wherein air at substantially atmospheric pressure isemployed in conjunction with the fuel injector to disperse and atomizethe fuel. For example, if the fuel injector is positioned in theinduction system close to the engine intake port, the fuel is injectedfrequently at a time when the air pressure in the intake port issubstantially less than atmospheric. Thus, if atmospheric air can beintroduced in proximity to the fuel injector, this air will be at ahigher pressure than the surrounding air and the fuel can be dispersedand atomized.

Most of the systems proposed for this purpose have had substantiallimitations. For example, if the system is employed in engines havingmultiple cylinders, the air assist is obtained from a manifold thatinterconnects all of the cylinders and hence the amount of air availableper cylinder is substantially reduced.

In order to avoid this problem, distributor valves have been proposed sothat air will be introduced at the cylinders in sequence. This increasesthe amount of air that is available, but has other disadvantages andlimits the applicability of the system to meet varying conditions.

It is, therefore, a principal object of this invention to provide animproved air-assisted injection system.

It is a further object of this invention to provide an improveddistributor valve for an air-assisted fuel injection system.

The air-assisted fuel injection systems previously proposed have beenutilized for only the single purpose aforenoted. That is, the air assisthas been employed only for the purpose of atomizing and mixing the fuelwith the air. However, in accordance with a number of features of thisinvention, it has been discovered that the assist air may be utilizedfor a variety of additional purposes.

For example, it is possible through the use of air assist to vary theair assist and the way the air is added so as to control the directionat which the fuel charge enters the combustion chamber.

It is, therefore, a still further object of this invention to provide anair-assisted fuel injection system wherein the air assist is employedfor controlling the direction of fuel flow into the combustion chamberof the engine.

In addition to controlling the direction of fuel flow, the air assistmay be employed for achieving results in addition to the control anddispersion of the fuel. For example, with conventional engine inductionsystems in normally aspirated engines, there is a lag in the time periodbetween when the intake valve opens and the intake charge actually flowsinto the combustion chamber. This is because the air in the inductionpassage is relatively stationary at the time the intake valve opens andit must be accelerated to a velocity to cause it to flow into thecombustion chamber. This gives rise to loss of volumetric efficiency andpumping losses.

In accordance with another object of the invention, an air assist systemis employed for introducing air into the combustion chamber immediatelyupon opening of the intake valve so as to avoid pumping losses andimprove volumetric efficiency.

Closely related to the aforenoted problem is a condition which resultsin what is referred to as "internal EGR" (exhaust gas recirculation).Because of the fact that there is an overlap between the opening of theintake valve and the closing of the exhaust valve, the pressure in thecombustion chamber may be higher than atmospheric at the time when theintake valve opens. Thus, rather than having a charge enter thecombustion chamber through the intake valve, some of the exhaust gasesmay flow into the induction system through the open intake valve. As thepressure in the cylinder decreases, the charge which is drawn into thecombustion chamber constitutes a fairly large percentage of exhaust gasand hence a condition a condition known as internal EGR exists. Thisobviously can be detrimental to running under some characteristics.

Therefore, it is a still further object of this invention to provide anair-assisted system for an engine wherein internal EGR may be controlledby introducing air at atmospheric pressure in the intake passage at thetime the intake valve is open and when there is an overlap between theopening of the intake valve and the closing of the exhaust valve.

Another condition which presents difficulties in obtaining good engineperformance is at idling. When the engine idles, the amount of airinducted is relative small and also is at a relatively low velocity.This causes a substantial reduction in turbulence in the combustionchamber and slow combustion. This, in turn, substantially reduces fueleconomy and deteriorates exhaust emission control.

It is, therefore, a still further object of this invention to improvethe idle operation of an engine by supplying a substantial portion ofthe idle air charged through the air assist system.

Normally the idle speed of an engine is controlled at least in part byeither varying the position of the throttle valve or by controlling theair flow through an idle bypass passageway that extends around thethrottle valve. These idle speed controlling methods generally result inrather poor idle speed running and idle speed control because of thefact that the adjustment of the idle air flow takes place a substantialdistance away from the combustion chambers.

It is, therefore, a still further object of this invention to try toprovide an improved method and apparatus for controlling idle speedthrough the use of an air assist system.

It has been previously noted that an important feature of the inventionresides in the ability to use the air assist to control the direction offuel flow into the combustion chamber. As has been noted, however, undercertain circumstances, the air charge that enters the combustion chamberis at a low velocity and in low amounts. This gives rise to incompletecombustion and other associated problems.

It is, therefore, a still further object of this invention to employ anair assist system for an engine that can be employed for introducingturbulence into the combustion chamber under certain running conditions.

In addition to increasing the velocity of air flow into the combustionchamber to increase turbulence, it is also desirable to provide a systemwherein the direction of air flow in the combustion chamber can becontrolled. Various flow controlling systems have been proposed for thispurpose. One disadvantage with such flow controlling systems is that inorder to induce turbulence in the combustion chamber, the intake passageis restricted and hence the high-speed performance of the engine can bedeteriorated.

It is, therefore, a still further object of this invention to employ anair-assisted system for an engine where the air assist can be employedto generate the desired type of flow pattern in the combustion chamberdepending upon the engine running condition.

As has been noted, one type of air assist system for multi-cylinderengines employs a sequentially operated valve for sequentially supplyingair to the individual fuel injectors associated with each cylinder.Normally this type of sequential valve is driven in timed relationshipwith the engine camshaft. Such an arrangement, however, does not permitthe attainment of a number of the objects which have been aforenoted.

It is, therefore, a still further object of this invention to provide animproved control valve for an air-assisted fuel injection system whereinthe timing and duration of the air assist may be controlled.

SUMMARY OF THE INVENTION

A first feature of this invention is adapted to be embodied in aninternal combustion engine having an induction system for delivering acharge to a combustion chamber of the engine. A fuel injector isprovided for injecting a fuel spray into the induction system. Means areprovided for injecting a stream of air at a pressure not substantiallygreater than atmospheric into the induction system and in proximity tothe area where the fuel spray passes. A control valve is provided forcontrolling at least one of the timing and duration at which the streamof air is injected.

Another feature of the invention is adapted to be embodied in anapparatus for injecting fuel into an internal combustion engine and iscomprised of a fuel injector having a spray nozzle for discharging aspray of fuel. A fitting is fixed relative to the fuel injector anddefines a channel through which at least a portion of the spray of fuelfrom the fuel injector passes. Means are provided for delivering airinto the channel in a path to atomize the fuel delivered from the fuelinjector and for redirecting the fuel spray.

Another feature of the invention is adapted to be embodied in aninternal combustion engine having a combustion chamber and an intakepassage communicating with the combustion chamber through an intakeport. An intake valve controls the flow through the intake port and isopened and closed in relation to the engine cycle. An auxiliary intakepassage opens into the intake passage in a direction toward the intakeport. Means deliver air through the auxiliary intake passage for only aportion of the time when the intake valve is opened.

A further feature of the invention is adapted to be embodied in aninternal combustion engine having a plurality of cylinders. At least oneintake passage serves each of the cylinders through a respective intakeport. A plurality of intake valves each controls the flow through arespective one of the intake ports. A camshaft is provided for operatingthe intake valves. Each of a plurality of auxiliary intake passagesintersects a respective one of the intake passages and are directedtoward the respective intake port. Control valve means are driven intimed relationship to the camshaft for controlling the opening andclosing of the auxiliary intake passages.

A still further feature of the invention is adapted to be embodied in acontrol valve means for use with an internal combustion engine having aconfiguration as described in the preceding paragraph. In this feature,the control valve is comprised of a valve body having an air supplypassage which is delivered to each of a plurality of valving segments.Each valving segment has a valving portion that cooperates with arespective one of the auxiliary intake passages for controlling the flowthrough that auxiliary intake passage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of an internal combustion engine constructedin accordance with a first embodiment of the invention, with portionsbroken away and shown in section and other portions shown schematically.

FIG. 2 is a partial cross-sectional view taken along the line 2--2 ofFIG. 1.

FIG. 3 is an enlarged cross-sectional view taken along the same plane asFIG. 2.

FIG. 4 is an enlarged top plan view of the area shown in FIG. 3 and isin part similar to FIG. 1.

FIG. 5 is a cross-sectional view taken along the line 5--5 in FIG. 3.

FIG. 6 is an end elevational view looking in the direction of the arrow6 in FIG. 5.

FIG. 7 is an enlarged cross-sectional view of the distributor valveshown in cross section in FIG. 1 and taken along a plane parallelthereto.

FIG. 8 is a cross-sectional view taken along the line 8--8 of FIG. 7.

FIG. 9 is a cross-sectional view taken along the line 9--9 of FIG. 8.

FIG. 10 is a cross-sectional view taken along the line 10--10 of FIG. 7.

FIG. 11 is a cross-sectional view, in part similar to FIG. 7, showing adistributor valve constructed in accordance with another embodiment ofthe invention.

FIG. 12 is a cross-sectional view taken along the line 12--12 of FIG.11.

FIG. 13 is a cross-sectional view taken along the line 13--13 of FIG.12, showing the distributor valve in one of its extreme positions.

FIG. 14 is a cross-sectional view, in part similar to FIG. 13, and showsthe distributor valve of this embodiment in the other extreme position.

FIG. 15 is a cross-sectional view taken along the line 15--15 of FIG.11.

FIG. 16 is a cross-sectional view, in part similar to FIGS. 8 and 12,and shows another embodiment of the invention.

FIG. 17 is a cross-sectional view taken along the line 17--17 of FIG. 16and shows the distributor valve in a first position.

FIG. 18 is a cross-sectional view, in part similar to FIG. 17, and showsthe distributor valve in another position.

FIG. 19 is a graphical view showing the amount of fuel and amount of airsupplied per cylinder per cycle in conjunction with a conventionalair-assisted system and one constructed in accordance with theinvention.

FIG. 20 is a timing diagram showing the intake valve opening, air assistdischarge, and fuel injection discharge to explain operational methodsthat may be practiced with the invention.

FIG. 21 is a timing diagram, in part similar to FIG. 20, and showsanother embodiment of the invention and also shows the relationship ofthe opening of the exhaust valve relative to the intake valve.

FIG. 22 is a graphical view, in part similar to FIGS. 20 and 21, andshows a further operational mode that may be practiced in conjunctionwith the invention.

FIG. 23 is a graphical view, in part similar to FIGS. 20, 21, and 22,and shows another operational mode that may be employed in conjunctionwith the invention.

FIG. 24 is a top plan view, in part similar to FIG. 1 and shows afurther embodiment of the invention.

FIG. 25 is a cross-sectional view taken along the line 25--25 of FIG.24.

FIG. 26 is a top plan view, in part similar to FIGS. 1 and 24, and showsa further embodiment of the invention.

FIG. 27 is a cross-sectional view taken along the line 27--27 of FIG.26.

FIG. 28 is a top plan view, in part similar to FIGS. 1, 24, and 26, of ayet further embodiment of the invention.

FIG. 29 is a cross-sectional view taken along the line 29--29 of FIG.28.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

Referring first to the embodiment of FIGS. 1-9, an internal combustionengine constructed in accordance with this embodiment is indicatedgenerally by the reference numeral 31. Since the invention dealsprimarily with the induction system and the fuel injection system forthe engine 31, the components of the engine 31 which are conventional orwhich may be of any known conventional structure are shown onlypartially and will be described only summarily. Reference may be had toany prior art engine for the basic construction of an engine with whichthe invention may be practiced. However, and as will become apparent,the invention does have particular utility in conjunction withhigh-performance engines having multiple valves per cylinder, and in theillustrated embodiment as will become apparent, the engine 31 isprovided with five valves per cylinder.

The engine 31 is comprised of a cylinder block 32 which, in theillustrated embodiment, is formed with four cylinder bores 33 in whichpistons 34 reciprocate. Although the invention is described inconjunction with a four-cylinder in-line type of engine, it will bereadily apparent to those skilled in the art how the invention may beutilized with engines having other cylinder numbers and other cylinderconfigurations. By way of example only, the cylinder block 32 may be ofthe V-type, and the illustrated arrangement may comprise that of onebank of two angularly disposed banks of cylinders with the inductionsystem being disposed in the valley between the cylinder banks.

The pistons 34 are connected by means of connecting rods (not shown) toa crankshaft, which is also not shown, in a known manner. As has beennoted, the invention deals primarily with the induction system and fuelinjection system for the engine 31 and, for that reason, furtherdescription of the lower end of the engine will not be made.

A cylinder head, indicated generally by the reference numeral 35, isaffixed to the cylinder block 32 in any well-known manner. The cylinderhead 35 has individual recesses 36 which cooperate with the cylinderbores 33 and pistons 34 to define the combustion chambers of the engine31.

One side of the cylinder head 35 is formed with Siamesed-type intakepassages, indicated generally by the reference numeral 37, each of whichhas a common inlet opening 38 in an outer side surface 39 of thecylinder head 35. This passage 37 branches into a center portion 41 anda pair of side portions 42 and 43 that terminate at respective valveseats. These valve seats comprise a center valve seat 44 and a pair ofside valve seats 45 and 46.

Although the invention is described in conjunction with an engine havingthree intake valves per cylinder served by a Siamesed-type intakepassage, it will be readily apparent to those skilled in the art how theinvention may be applied with engines having separate intake passagesand with different numbers of intake valves including only one intakevalve per cylinder. However, certain facets of the invention haveparticular utility in conjunction with multi-valve engines, andparticularly with those embodying Siamesed intake passages for reasonswhich will become apparent.

A center intake valve 47 and a pair of side intake valves 48 cooperatewith the valve seats 44 and 45 and 46, respectively, to control the flowtherethrough. These intake valves are each supported in the cylinderhead 35 by respective valve guides 49 that are cast or pressed in place.The orientation of the intake valves 47 and 48 and configuration of theintake passage 37 may be of the type described in the copendingapplication entitled "Engine Air Intake Device," Ser. No. 08/354,539,filed Dec. 13, 1994, in the name of Masaaki Yoshikawa, and assigned tothe assignee hereof. Also, the shape of the combustion chamber may be asdefined in that application, and the disclosure of that application isincorporated herein by reference. Again, it is to be understood thatthis configuration is only one of many with which the invention may bepracticed.

Coil compression springs 51 encircle the stems of the respective intakevalves 47 and 48 and act against the cylinder head 35 and keeperretainer assemblies (not shown) affixed to the stems of the valves 47and 48 for urging them to their closed positions. Thimble tappets 52 areslidably supported in the cylinder head 35 and are engaged by the lobes53 of an intake camshaft 54 for opening the intake valves 47 and 48. Theintake camshaft 54 is journalled in the cylinder head 35 for rotation ina suitable manner and is driven at one-half crankshaft speed by asuitable timing drive.

The induction system which supplies the intake charge to the cylinderhead intake passages 37 will be described later.

On the side of the cylinder head 35 opposite from the intake passages 37there are provided exhaust passages 55 which, like the intake passages37, may be either Siamese or separate. These exhaust passages 55 extendfrom valve seats 56 formed in the cylinder head 35 and terminate in anouter surface 57 of the cylinder head 35 which is disposed opposite tothe surface 38 through which the intake passages 37 extend. An exhaustmanifold (not shown) is affixed to the cylinder head surface 57 forcollecting the exhaust gases and discharging them to the atmospherethrough any suitable exhaust system.

A pair of exhaust valves 58 are slidably supported in the cylinder head35 by pressed or cast-in valve guides 59. The axes of reciprocation ofthe exhaust valves 58 may also be as described in the aforenotedcopending application, Ser. No. 08/354,539.

Coil compression springs 61 encircle the stems of the exhaust valves 58.These springs 61 act against keeper retainer assemblies (not shown)affixed to the upper ends of the stems of the exhaust valves 58 andsurfaces of the cylinder head 35 for urging the exhaust valves 58 totheir closed positions.

Thimble tappets 62 are slidably supported in bores in the cylinder head35 and engage the keeper retainer assemblies for actuating the valves58. The thimble tappets 62 are, in turn, operated by the lobes 63 of anexhaust camshaft 64 that is rotatably journalled in the cylinder head 35in a known manner. Like the intake camshaft 54, the exhaust camshaft 64is driven by a suitable drive from the crankshaft of the engine atone-half crankshaft speed. A portion of this drive appears in FIG. 1 andis identified by the reference numeral 65. This speed reduction may takeplace in one or more stages from the crankshaft, as noted in theaforenoted copending application, Ser. No. 08/354,532.

The engine 31 as thus far described may be considered to be the same asthat disclosed in copending application Ser. No. 08/354,539.Alternatively, the invention may be employed in conjunction with anyconventional type of engine. As has been noted, the invention dealsprimarily with the induction system and fuel injection system for theengine 31, and this induction system is indicated generally by thereference numeral 66.

The induction system 66 is comprised of an air inlet device 67 having aninlet opening 68 through which atmospheric air is drawn. The air inletdevice 67 may include a filter element and a mechanism of any known typefor silencing the air which is inducted. This air is then delivered tothe inlet conduit 69 of a plenum chamber 71 which extends along one sideof the engine adjacent the cylinder head surface 38. An air flow meter72 is interposed between the air inlet device 67 and the plenum chamberinlet 69 and measures the volume of air flowing through the engine forthe engine management system. Except as will be noted, this enginemanagement system may be of any known type.

The plenum chamber 72 has branch outlets 73 which extend to a throttlebody 74 which has individual passages 75, each of which communicateswith a respective one of the cylinder head intake passages 37 fordelivering the air flow from the induction system 66 to the combustionchambers of the engine. A throttle valve shaft 76 extends transverselythrough the throttle body 74 and has butterfly-type throttle valves 77affixed to it in each passage 75 for controlling the flow therethrough.These throttle valves 77 and the throttle valve shaft 76 are actuated ina known manner.

Each of a plurality of fuel injectors, indicated generally by thereference numeral 78, is mounted in the cylinder head 35 in a manner tobe described for spraying a fuel charge into the intake passages 37. Thefuel injectors 78 may be of any conventional type, and preferably arethe type that are provided with an electrically operated injector valvewhich, when actuated, causes a spray of fuel to be emitted from thenozzle portion of the fuel injector 78. A fuel rail (not shown) isaffixed to the injector 78 for supplying fuel to them at a regulatedpressure, as is well known in this art.

In accordance with an important feature of the invention, the fuelinjectors 78 have their nozzle portions 79 mounted in insert pieces,indicated generally by the reference numeral 81, which are received inbores 82 formed in the outer end of the cylinder head surface 39adjacent to and intersecting the induction passages 37. The bores 82are, in fact, counterbores formed at the outer end of a smaller diameterfuel passage 83 which extends to and intersects the intake passage 37.

These insert pieces 81 are formed with a cylindrical recess 84 adjacenttheir outer periphery and which is sealed relative to the counterbore 82by means of O-rings received in sealing grooves 85 and 86 formed onopposite sides of the recess 84. This recess 84 therefore forms an airchamber 87 to which air is supplied at atmospheric pressure in a mannerwhich will be described later.

The insert piece 81 is formed with a first bore 88 that is complementaryto and which receives the nozzle portion 79 of the fuel injector 78. AnO-ring seal 89 is received in a groove formed around the bore 88 andeffects a fluid-type seal between the insert piece 81 and the injectornozzle portion 79.

At the base of the bore 88, the insert piece 81 is formed with a fueldischarge passage 91 which has a configuration as best shown in FIGS.3-6 and which is oval shaped at its discharge end, as clearly shown inFIG. 6, and which tapers generally outwardly from the bore 88 in whichthe injector nozzle portion 79 is received. As may be best seen in FIG.4, the taper of the discharge port 91 of the insert piece 81 isconfigured so that a fan-type path exists from the fuel injector nozzle79 toward the intake passage portions 41, 42, and 43. This fan-shapedpath is defined between the phantom lines 92 in FIG. 4, and it will beseen that it encompasses both the center intake valve seat 44 and theadjacent portions of the side intake valve seats 45 and 46.

In accordance with the invention, however, the air which is introducedalong with the fuel is introduced through a plurality of openings whichwill be described and which are configured so as to direct and confinethe fuel spray from the nozzle, which fuel spray path is indicated bythe phantom lines 93 in FIGS. 4 and 5. In this way the air that isinjected along with the fuel can be employed to control the spray path,and this spray path can be altered during engine running by changing thetiming of the introduction of air through these ports, as will also bedescribed.

In the illustrated embodiment, there are provided a first series of airpoets 94 (FIG. 3) which are disposed on the narrow side of the fueldischarge opening 91, and thus have only a small amount of control overthe fuel discharge path. However, on the plane perpendicular to thisplane, as seen in FIG. 5, there are provided a plurality of openings 95on opposite sides of the flow path through which the air will flow, asshown by the arrows in FIG. 5 and which will confine the fuel spray tothe narrower path 93 than that of the air flow path 92 from thedischarge opening 91. Thus, the fuel may be controlled so that it willprimarily flow through the center intake valve seat 44 when the airpressure is introduced at the time when the injector 78 is discharging.

On the other hand, if the air is introduced at a time other than whenthe injector 78 is discharging fuel, then the fuel will pass through thelarger spray path, indicated by the lines 92, and be delivered throughnot only the center intake valve seat 44, but also through the sidevalve seats 45 and 46. Therefore, by controlling the time of theintroduction of air through the insert piece 81, the spray path of theinjector 78 can be controlled during engine running. This permits theattainment of stratification under certain running conditions asdesired. This concept may be employed in conjunction with an air flowcontrol of the type as also described in the aforenoted copendingapplication, Ser. No. 08/354,539, so as to further improve engineperformance.

The system for supplying the air for the assist in the operation of thefuel injector 78 will now be described by primary reference to FIGS.1-3, and 7-10. This system draws air from the plenum chamber 71 througha fitting 96 and conduit 97 to a control valve assembly, indicatedgenerally by the reference numeral 98. This control valve assembly 98has an inlet fitting 99 to which the conduit 97 is affixed. The fitting99 is affixed to a main body portion 101 of the control valve 98. A bore102 interconnects the fitting 98 with a longitudinally extending bore103 formed in the valve body 101.

A rotary-type control valve element 104 is journalled suitably in thebody 101. End seals 105 provide a seal between the valve element 104 andthe body 101. This valve 104 has a longitudinally extending blind bore106 which extends of sufficient length to encompass four distributorpassages 107, one for each cylinder which the control valve 98 serves.The outer end of the blind bore 106 is closed by a closure plug 108.

The bore 106 of the valve element 104 receives air from the housing bore102 through a plurality of radially extending drillings 109 which areformed in the valve element 104 in aligned relationship with the bore102.

In addition to the openings 109 that permit air to enter into the bore106 of the valve element 104, the valve element 104 is also providedwith a plurality of axially spaced slotted openings 111, one for eachdischarge port 107. The openings 111 will, when in registry with theopenings 107, permit air to flow through the valve element 104 todischarge fittings 112 of the valve housing 101. These dischargefittings 112 are connected to individual conduits 113 that extend acrossthe engine and which are connected to fittings 114 fixed in the cylinderhead 35 and which communicate with the recesses 87 formed by the insertpieces 81.

Hence, when the opening 111 of the control valve 104 is in itsregistering position with the respective fitting 107, then air will beintroduced into the induction system through the insert piece 81. Thisair is at substantially atmospheric pressure, and thus will be at ahigher pressure than the pressure in the intake passages 37 when therespective intake valves 47 and 48 are open. As a result, there will bea pressure differential, and the air that is introduced through theinsert piece 81 will flow at a higher velocity than the air in theintake passage 37 because of its higher pressure, at least duringinitial opening of the intake valves 47 and 48. This will help in notonly atomizing the fuel injected by the fuel injector 78, but also willbe useful in controlling the spray path, as aforenoted. In addition,this air flow can be utilized to minimize pumping losses, controlinternal EGR, control engine idle operation and for a variety of otherpurposes, as will be described.

In order to control the timing and duration of the air assist, the valveelement 104 is driven from the drive for one of the camshafts, theexhaust camshaft 64 in this embodiment, as shown in FIGS. 1 and 2. Tothis end, a pulley 115 is affixed to the exposed end of the valve shaft104 and is driven by a toothed belt 116 from the exhaust camshaft 64. Apulley 117 is affixed to the exhaust camshaft adjacent its drive 65 fordriving the toothed belt 116. The drive for the valve shaft 104 mayinclude any known type of variable valve timing mechanism for changingthe timing at which the individual flow control ports 111 register withtheir controlled openings 107 for controlling the timing of the airassist. The duration of the air assist may be controlled by selectingthe circumferential width of the slots 111.

It should also be noted that the slots 111 are circumferentially spacedaround the axis of the valve element 104, and this is done so as tocorrespond with the respective intake cycles for each of the cylinderbores 33 and the time when their respective intake valves 47 and 48 areactivated. As will also be described, the air assist may begin at anytime when the intake valves 47 and 48 are opened and, in fact, may beginbefore they are opened so as to reduce pumping losses.

In this embodiment of the invention, the air assist is also employed forcontrolling the idle speed and idle operation of the engine. Thus, inthe conduit 97 there is provided an idle speed control valve, which isshown schematically and indicated by the reference numeral 118. Thisidle speed control valve 118 is operated by an ECU 119 in any desiredcontrol strategy. As is well known in the art, such idle speed controlvalves are employed to vary the amount of air supplied to the engineduring idling operation, and thus provide fine tuning for engine idlespeed. Since this idle speed control valve 118 is positioned downstreamof the air flow meter 72, the amount of air flowing to the system duringidle will also be measured, and accurate control of the fuel injectionamount is also possible.

Finally, the engine 31 is provided with a crankcase ventilation systemthat includes a crankcase ventilating manifold 121 which receivescrankcase gases from a conduit 122 and supplies them through dischargeportions 123 into the throttle body 74, and specifically its passages 75downstream of the flow controlling throttle valve 77.

In the embodiment of the invention as thus far described, the air assistsystem is capable of changing the timing of the opening and closing ofthe additional air supply through the control valve 98. In someinstances it may also be desirable to be able to change the duration ofair assist, and FIGS. 11-15 show a first embodiment of flow controlvalve that achieves this end. Since this is the only difference betweenthis embodiment and that of FIGS. 1-10, only the flow control valve isillustrated and is identified generally by the reference numeral 151.The flow control valve 151 has a valve body 152 which, like thepreviously described embodiment, is provided with an inlet fitting 153that communicates with a source of air at substantially atmosphericpressure.

The fitting 153 communicates with a radially extending passageway 154formed in the valve body 152 and which intersects an axially extendingbore 155. A control valve element 156 is rotatably journalled withinthis bore 155 and is formed with a hollow interior 157. This hollowinterior communicates with the source of air pressure through aplurality of circumferentially spaced passages 158 that are axiallyaligned with the housing bore 154, so that air at atmospheric pressurewill be present in the hollow interior of the valve element 156.

Unlike the previously described embodiment, the valve element 156 issupported for axial movement in the housing bore 155. A coil compressionspring 159 is received in a housing extension 161 and bears against abearing member 162 which engages a closure plug 163 fixed to the valveelement 156 so as to normally urge it into abutment with one end of thehousing 152. A seal 164 seals the valve element 156 at this end of thehousing.

The opposite end of the valve element 156 has a male splined portion 165that is received within a female spline opening 166 of a valve elementdriving shaft 167. This driving element 167 is rotatably journalled inthe opposite end of the housing 152 and has a pulley (not shown)connected to its outer end for driving through a variable valve timingmechanism from one of the camshafts of the engine in the mannerpreviously described.

A sliding piston 168 is received at the base of the female splines 166and defines a pressure chamber 169 in which a further coil compressionspring 171 is received. The spring 171 is lighter than the spring 169,so that the valve element 156 will be normally urged to the positionshown in FIG. 11. This position is also shown in FIG. 13.

In order to pressurize the chamber 169 and effect axial movement of thevalve element 156 to change the duration of air injection, the chamber169 is communicated with a source of pressure such as the oil pump 172of the engine. The oil pump 172 is shown schematically in this figureand communicates with a passageway 173 in the housing 156 thatcommunicates with the chamber 169 through a plurality ofcircumferentially spaced passages 174 drilled in the driving shaft 167.

A return passageway 175 also communicates with the chamber 169 through aplurality of circumferentially spaced ports 176. A control valve 177controls the communication of the passageway 175 to the oil tank 178 ofthe engine. When the control valve 177 is actuated to close the returnpassageway 175, then the pressure in the chamber 169 will raise, and thevalve element 156 will be urged in the direction of the arrow 179 so asto effect a change in the duration of air injection.

Rather than the single slotted openings for controlling thecommunication of the interior 157 of the valve element 156 with the airinjectors, the valve element 156 is provided with a plurality of steppedopenings having a narrow portion 181 which gives a short duration and alarger portion 182 which gives a longer duration of air assist. Theseslots 181 and 182 communicate with respective passages 183 formed in thehousing 152. These openings 183 are aligned with the slots 181 and 182,but are narrower than the combined width of the slots 181 and 182. Thehousing openings 183 have an axial length that is slightly less than thelength of the individual slotted portions 181 and 182, as clearly shownin FIGS. 13 and 14.

The slotted openings 183 in the housing 152 communicate with respectivefittings 184 to which flexible conduits 185 are connected. The conduits185 communicate with the insert pieces 81, as previously described, andfor that reason this connection is not illustrated in these figures.

When the desired control strategy requires a short duration of airassist, then the control valve 177 is maintained in its opened conditionso that there will be little fluid pressure in the chamber 169 and thevalve element 156 will be held in the position shown in FIGS. 11 and 13.However, when the control strategy requires a longer duration, thecontrol valve 177 is closed so that the valve element 156 will be movedin the direction of the arrow 179 to the position shown in FIG. 14. Inthis condition there is a longer duration of air assist. As previouslynoted, the reasons for these variations in engine performance will bedescribed later.

A control valve constructed in accordance with a further embodiment ofthe invention is illustrated in FIGS. 16-18. This control valve isindicated generally by the reference numeral 201 and differs from thecontrol valve of the embodiment of FIGS. 11-15 in that it provides acontinuously variable duration, rather than a stepped duration, as thatearlier embodiment. Since this is the only difference between thisembodiment and that of FIGS. 11-15, only three figures are necessary toillustrate this embodiment, and these three figures correspond to FIGS.12, 13, and 14, respectively, of the earlier embodiment.

Since the variation in duration is achieved only by changing theconfiguration of the slot, indicated generally by the reference numeral202, and all other components are the same, where the components are thesame, they have been identified by the same reference numerals and willnot be described again. As may be seen, the slot 202 has a continuoustaper from one end to the other. Therefore, by changing the axialposition of the valve element 156, it is possible to vary continuouslythe duration of air assist. Since this is the only difference from thepreviously described embodiment, and since the axial movement can beachieved by a mechanism as described in conjunction with the embodimentof FIGS. 11-15, further description of the operation of this embodimentis not believed to be necessary to permit those skilled in the art topractice the invention.

As has been noted, conventional air-assisted injection systems utilizethe air primarily for assisting in the dispersion of the fuel and theatomization of the fuel, as well as mixing it with the air. However andas has already been noted, the air assist may be employed for otherpurposes, such as redirecting the fuel spray or changing the spraypattern during engine running. In addition, the air can be utilized tocontrol the idle speed, reduce pumping losses, and generate turbulencein the combustion chamber. This is possible in part due to the type ofcontrol valves which are employed and which have been shown in theembodiments of FIGS. 1-9, 10-15, and 16-18.

FIG. 19 is a view showing how this type of valve permits a greateramount of air flow for the air assist system than the previouslyemployed control valves utilized in air assist systems, if any controlvalve at all is used. The previously employed control valves with airsystems have operated like rotary valves where the ports supplied aresequentially registered with a single opening in the rotating valveelement. As a result of this, not only is the amount of air availablefor air assist limited, but the timing and duration cannot be easilychanged.

FIG. 19 is a graphical view wherein the dotted line shows the amount ofconventional air assist in relation to fuel charged and total air chargefor the engine. The amount of air available with the conventional typeof valve is indicated at C, and this is the total amount of bypass airdivided by the number of cylinders. With this invention, however, theamount of air available is substantially greater, as indicated at B, andthis can be a substantial portion of the total air which passes throughthe throttle valve for the engine. In fact, at idle, the total airsupplied for idle operation can at times be supplied only through theair assist system if this is desired.

Referring now to FIG. 20, this is a timing chart for a four-cylinderengine and shows the timing during slightly more than two completerevolutions of the crankshaft, and specifically the intake events. Theintake valve opening and closing for each cylinder is shown, and theengine is described as having a firing order 1-3-4-2, a fairly typicalfiring order for a four-cylinder engine.

The fuel injection F1 takes place from the fuel injectors 78 at a timeapproximately midway between the intake valve opening and intake valveclosing. Of course, the duration of fuel injection will vary undervarying running conditions, and the time interval shown is just typicalof a particular engine running condition and is depicted to show thevarious concepts that can be employed.

The air assist time intervals are shown, with the total air assist inthis particular embodiment being shown by a broken-line view that beginsat a time period A1 before intake valve opening. This air assist beforeintake valve opening causes the engine to experience less pumpinglosses. The reason for this is that when the intake valve normally opensand without air assist, the pressure in the induction system upstream ofthe intake valve, and specifically in the intake passage 37, may stillbe less than atmospheric because of the fact that the time since theprevious intake valve opening is so small that the pressure has not hada chance to stabilize. Thus, by introducing air at atmospheric pressureduring the time period A1, the pumping losses will be reduced, and also,the amount of internal EGR that takes place will be reduced. Thus, byvarying the time period A1, pumping losses can be reduced and the amountof internal EGR can be controlled.

The time period when air assist takes place once the intake valve isopened also can be employed to create turbulence in the combustionchamber. Because of the fact that the assist air is at a higher pressurethan the inducted air, the velocity of this air will be greater. Also,since the flow area through which the assist air is introduced issmaller, the high-velocity charge can also be directed through the shapeof the passageway in which the air is injected. This can cause desiredmotions in the combustion chamber, depending upon the direction. Eitherswirl or tumble or both can be generated by appropriately directing theair charge.

The assist air A3 that flows when the fuel is injected also, aspreviously noted, is effective in breaking up the fuel particles andcausing them to atomize or vaporize.

It should be noted that the pumping loss problem is one that isparticularly attendant with engines wherein there is an individualthrottle valve for each cylinder head intake passage, as with theembodiments thus far described. An embodiment having a common throttlevalve for all intake passages will be described later by reference toFIGS. 24 and 25.

FIG. 21 is a timing diagram that is partially similar to FIG. 20, butthis also shows the events of the exhaust valve and wherein the airassist is effective in reducing internal EGR under light load andlow-speed conditions. By causing air assist to take place all of thetime when the intake valve is opened, and particularly during the timeperiod when the exhaust valve still is open, internal EGR will besubstantially eliminated. Of course, at some times some internal EGR maybe required or desired, and this can be promoted by delaying thebeginning of air assist.

FIG. 22 is a timing diagram, in part similar to that of FIG. 20, butalso shows the opening of the exhaust valve. This arrangement isparticularly useful where there is a single throttle valve for eachintake passage of the engine and wherein pumping losses and internal EGRcan become a greater problem. By advancing air assist so that it beginsbefore the intake valve is opened, pumping losses can be reduced, as canthe amount of internal EGR.

In engines having a single throttle valve positioned upstream from theindividual cylinder head intake passages and controlling the total airflow, there is less rapid response to changes in throttle position, butthe pumping loss and internal EGR problems are somewhat less. With suchengines, a timing diagram, as shown in FIG. 23, can be employed whereinthe air assist time period is either the same as the fuel injection timeor only slightly longer than the fuel injection time. Of course, thiseliminates the advantage of increasing turbulence in the combustionchamber, and it may be desired to utilize longer air assist periods orearlier air periods, even in such engines so as to generate turbulenceto improve combustion at low speeds and low loads.

As has been noted, the invention is susceptible of use with engineshaving a single throttle valve for controlling the air flow to amultitude of cylinders. FIGS. 24 and 25 show such an embodiment. Thisembodiment differs from the embodiment of FIGS. 1-10 only in thethrottle control for the engine, and since all other components are thesame as that previously described, they have been identified by the samereference numerals and will not be described again.

In this embodiment, the throttle body 74 may be retained or may betotally eliminated. However, a single flow controlling throttle valve,indicated generally by the reference numeral 251, is mounted in theinlet portion 69 of the plenum chamber 71. Thus, the throttle valve 251is still downstream of the air flow meter 72, and hence, all air flowingto the engine will have passed through the air flow meter 72 so that theamount of fuel injected can be accurately controlled in relation to theactual air flow.

With this embodiment, since the throttle valve 69 is positioned upstreamof the plenum chamber 71, the conduit for the air assist system isprovided with an inlet 252 that is upstream of the throttle valve 251 inthe plenum chamber inlet 69. However, this fitting 252 is stilldownstream of the air flow meter 72. The conduit 97 going to the idlespeed control valve 118 and to the air control valve 98 is connected tothis fitting 251. In all other regards, this embodiment is constructedand operates the same as those previously described, and for thatreason, further description is not believed to be necessary.

It has been noted that one of the uses of the assist air may be tocreate turbulence in the combustion chamber. Although this can be doneby introducing the air through the insert piece 81 of the previouslydescribed embodiments, the assist air may be introduced separately intothe intake passage in addition to through this insert piece. FIGS. 26and 27 show another embodiment of the invention wherein a separate airpassage is provided in addition to that of the insert piece. Thisembodiment is generally the same as the embodiment of FIGS. 1-10, andwhere components are the same or substantially the same as thatembodiment, they have been identified by the same reference numerals andwill not be described again.

In this embodiment, the control valve 98 is driven off of the intakecamshaft rather than the exhaust camshaft, as with the previouslydescribed embodiments. This is really not significant unless there is avariable valve timing mechanism employed between the crankshaft and thecamshafts. If such is the case, then it is desirable to drive thecontrol valve 98 off of the intake valve, even if there is a variablevalve timing mechanism between the control valve 98 and the camshaftwhich drives it, the intake camshaft 24 in this embodiment.

Also, the crankcase ventilation system does not discharge into theinduction system in this particular embodiment.

In addition to supplying air to the insert pieces 81 through theconduits 113, there is provided a branch conduit 301 that communicateswith a swirl passage 302 formed in the cylinder head and whichintersects one of the side intake passages 42 or 43 on one side thereof.Thus, the swirl ports 302 will introduce a swirling motion, as shown bythe arrow 303 in FIG. 27 when the intake valve is opened. This swirlingmotion will cause turbulence in the combustion chamber, which isparticularly useful at low-speed, low-load conditions. Turbulence hasbeen found to improve flame propagation and ensure complete combustion.

It should be noted that the fuel injector 78 of this embodiment is ofthe dual-nozzle type. Each nozzle has a spray pattern, indicated by thearc 303 in FIG. 26, so that the combined spray pattern of the twonozzles is greater than that of a single nozzle, as indicated by the arc304. In all other regards, this embodiment is the same as thosepreviously described, and various timing arrangements can be employedfor achieving desired purposes.

FIGS. 28 and 29 show another embodiment of the invention which is thesame as that of FIGS. 26 and 27, but also adds the crankcase ventilationsystem, as used in the embodiment of FIGS. 1-10 and which has,therefore, been identified by the same reference numerals as applied inthose figures.

It should be readily apparent from the foregoing description that thedescribed embodiments of the invention provide an air-assisted fuelinjection system wherein the air is employed not only to disperse andatomize the fuel, but can be employed for other purposes such ascontrolling idle speed, reducing pumping losses, inducing turbulence inthe combustion chamber to improve flame propagation, controllinginternal EGR, and various other purposes. These results are achieved, atleast in part, due to the use of the novel control valves that controlthe auxiliary air flow. Of course, the foregoing description is that ofpreferred embodiments of the invention. Various changes andmodifications may be made without departing from the spirit and scope ofthe invention as defined by the appended claims.

I claim:
 1. An apparatus for injecting fuel into an internal combustionengine comprising a fuel injector having a spray nozzle for discharginga spray of fuel, an insert piece fixed relative to said fuel injectorand defining a fan shaped channel through which at least a portion ofthe fuel from said injector passes, said channel tapering in one planarcross section from a narrow inlet end for receiving fuel and terminatingin a wider outlet end from which fuel is discharge, the width of saidchannel in a perpendicular cross section plane being substantiallyconstant along the length of said channel for creating a fan shapedspray pattern, and means for delivering air into said channel at a pointto atomize the fuel delivery from said fuel injector and redirect thespray of fuel.
 2. An apparatus as forth in claim 1, wherein thefan-shaped channel has a relatively narrow width relative to its length.3. An apparatus as set forth in claim 1, wherein the means fordelivering air into the channel comprises a plurality of radiallyextending air passages formed in the insert piece and intersecting thechannel.
 4. An apparatus as set forth in claim 1, wherein the airpassages are arranged so that there are more air passages on one side ofthe channel than the other for redirecting the spray of fuel.
 5. Anapparatus as set forth in claim 1, wherein the insert piece is formedwith a circumferential groove around its outer periphery into which theair passes extend and to which the supply of air is delivered.
 6. Anapparatus for injecting fuel into an internal combustion enginecomprising a fuel injector having a spray nozzle for discharging a sprayof fuel, an insert piece fixed relative to said fuel injector anddefining a channel through which at least a portion of the fuel fromsaid injector passes, and means for delivering air into said channel ata point to atomize the fuel delivery from said fuel injector andredirect the spray of fuel said insert piece directing fuel to acombustion chamber through an induction that serves the combustionchamber through a plurality of intake valve seats, each valve by arespective poppet-type valves, said channel and said delivered air beingarranged that the air when delivered directs the fuel toward less thanall of said intake valve seats and when no air is delivered through saidinsert piece the is fuel is directed toward all of the intake valveseat.
 7. An apparatus as set forth in claim 1, wherein the redirectionof the spray is toward at least one specific valve seat.
 8. An apparatusas set forth in claim 1, wherein the delivered air is at substantiallyatmospheric pressure.
 9. An induction system for an internal combustionengine having a combustion chamber with a volume that varies cycliclyduring a cycle of engine operation, an intake port for admitting an aircharge to said combustion chamber, means for cyclicly opening andclosing said intake port for controlling the admission of an air chargeto said combustion chamber, means defining an air chamber communicatingwith said intake prot for supplying an air charge to said intake port,means for adjusting the effective volume of said air chamber in responseto at least one engine running condition during at least a range ofoperation of said engine for controlling the volume of air which issupplied to said combustion chamber form said air chamber during asingle intake cycle, and control valve means for communicatingatmospheric air to said air chamber during the portion of the enginecycle when said intake port is closed.
 10. The induction system for aninternal combustion engine as set forth in claim 9, wherein the volumeof the air chamber is adjusted in response to the operator demand andthe load on the engine.
 11. The induction system for an internalcombustion engine as set forth in claim 10, wherein there is nothrottling of the air delivered to the combustion chamber by theinduction system.
 12. An induction system for an internal combustionengine as set forth in claim 8, wherein the induction passage serves thecombustion chamber through a plurality of intake valve seats, each valveby a respective poppet-type valve.
 13. An induction system for aninternal combustion engine as set forth in claim 12, wherein theredirection of the spray is toward at least one specific valve seat. 14.An induction system for an internal combustion engine as set forth inclaim 13, wherein the delivered air is at substantially atmosphericpressure.
 15. The induction system for an internal combustion engine asset forth in claim 7, wherein there is provided a first valve forcontrolling the effective volume of the air chamber and wherein thecontrol valve means comprises a second valve controlling the flow to theair chamber from an atmospheric air inlet.
 16. The induction system foran internal combustion engine as set forth in claim 15, wherein thefirst valve comprises a sliding piston.
 17. The induction system for aninternal combustion engine as set forth in claim 16, wherein the volumeof the air intake port served by a respective air chamber, theatmospheric air source for said chambers comprising a common source inwhich the third valve is positioned.
 18. The induction system for aninternal combustion engine as set forth in claim 6, wherein the airchamber comprises a cylindrical chamber and the first control valvecomprises a rotary valve.
 19. The induction system for an internalcombustion engine as set forth in claim 18, wherein the rotary valvecommunicates the cylindrical chamber with a further chamber when therotary valve is in a fully opened position.
 20. The induction system foran internal combustion engine as set forth in claim 1, wherein theclosed chamber is closed from the atmosphere.
 21. The induction systemfor an internal combustion engine as set forth in claim 20, furtherincluding a third valve for controlling the flow of atmospheric air tothe second valve.